A lot of sanding, scraping, cutting and clearing had to happen before they could transform the space into the work of art.

"When we came in, there were people living back here," Crow said. "There were a lot of bushes that we had to clean up. If you notice, we gave it a good cleaning -- even the wall got a lot of nurturing and a good cleaning itself."

The artists spent 12 days working along a cramped pathway just a few feet above the busy freeway.